As an avid user of cellular devices every phone that I have owned in the last 3 years has had a case on it. Whether it was just a silicon gel, hard plastic or even heavy duty to the likes of Otterbox Defender/Ballistics HC. I have spent countless amounts of money protecting my phones and may have dropped three of the multitude of phones I have owned. With the aesthetically beautiful phones coming out as of late I decided when I purchased my Samsung Galaxy Nexus that I would only use a screen protector, no other casing.
Here is my trial:
December 2011 Samsung Galaxy Nexus Never dropped
January 2012 Traded Nexus for Samsung Galaxy Note. Never dropped
March 2012 Sold Note and bought another Galaxy Nexus. Changed from Zagg Invisible Shield to Dynaflo Liquid armor. Never dropped
April 2012 Sold Nexus then bought HTC One X. One two foot drop and the screen splintered and cracked.
May 2012 Purchased another GNex to be back up to my One X after it gets back from HTC to fix broken glass. This puppy had a case put on it since day one. It has seen two drops and no damage.
June 4th-17th Used an iPhone 4S as I was selling my GNex again. Took a few drops in cases but no damage to the phone.
So after this unforeseen accident with the HTC One X I have gone back to the idea that the upfront cost of a case ($20-$50) is well worth it instead of the cost of out of warranty repairs, $130 this time from HTC. So in the end the choice is ultimately yours but with all the broken phones I have seen in the past 10 years, mainly customers and friends I would always recommend encasing your smart phone.
Zagg Invisible Shield